When two portions of a coherent light beam are directed at different angles against a surface of a chip of photorefractive material, light from one of the beams is tranferred to the other beam. Thus, one of the beams passing through the chip and emerging from an opposite surface of the chip has a reduced intensity, while the other beam that has passed through the chip and emerged has an increased intensity.
A two-dimensional array of beams representing the image of an object, can include beams of such a large range of intensities that sensors cannot detect the complete intensity range. One example is the detection of objects in a landscape by directing an intense beam at the landscape and forming an image of the landscape onto a video camera sensor surface. If there is a mirror-like reflecting surface in the landscape, light from such a reflecting surface may be so intense or bright compared to the rest of the landscape, that the camera sensor is overwhelmed and "blooming" occurs which degrades the portion of the image around the bright spot. Even if only the bright region is affected by the sensor, this is deleterious because the sensor does not indicate differences in brightness between extremely bright and very bright areas. An apparatus which could compress the range of intensities of the rays of light representing an image, as by amplifying (possibly by less than 1.0) very bright rays by much less than dim rays, would facilitate image detection by available sensors.